Alkali metal soaps of rosin and rosinfatty acid mixtures



United States Patent Ofi ice 3,l35,598 Patented June 2, 1964 3,135,698 ALKALI WTAL SOAPS F ROSIN AND RGSHN- FATTY ACID MHXTURES Charles M. Lambert, New London, Pa, assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Filed June 23, 1960, Ser. No. 38,109 5 Claims. (Cl. 25236S) This invention relates to alkali metal soaps of disproportionated rosin and disproportionated rosinfatty acid mixtures having improved stability against crystallization and to a method of preparing same.

In recent years, efforts to improve the physical properties of the sodium and potassium soaps of disproportionated rosin for use as emulsifiers in the synthetic rubber industry have moved consistently in the direction of higher solids and higher acid number soaps. This has increased the tendency of such soaps toward crystallization. In addition, the disproportionated rosin on which these soaps are based is being produced at gradually increasing acid numbers, and concurrently, with higher dehydroabietic acid content. These properties in the resin further enhance the possibility of crystallization in a given soap.

Since crystallization of these soaps is a serious disadvantage, attempts have been made to prevent it as by formaldehyde treatment, addition of dimer acids and the like. While these have given satisfactory inhibition against crystallization, they are subject to the disadvantage that when used in emulsion polymerization processes for the manufacture of synthetic rubber, they retard the rate of polymerization.

A principal object of the present invention, therefore, is to inhibit crystallization in alkali metal soaps of dispro portionated rosin and disproportionated rosin-fatty acid mixtures without impairing their efiiciency as emulsifiers in emulsion polymerization processes.

It has now been found that crystallization is strikingly inhibited in alkali metal soaps of disproportionated rosin and disproportionated rosin-fatty acid mixtures by the inclusion therein of from about 5% to 20% by weight, based on the weight of disproportionated rosin, of tetrahydro rosin acids, such as tetrahydroabietic and tetrahydropimaric, which have been neutralized, at least partially, with alkali. The tetrahydro rosin acids may be added as such but are preferably added in the form of a mixture as contained, for example, in substantially completely hydrogenated rosin. Soaps so treated are resistant to crystallization over relatively long periods of time. Moreover, this improvement in crystallization inhibition is obtained without impairing emulsifier efiiciency in the polymerization process.

Having described the invention generally, the following examples are given to illustrate specific embodiments thereof. Parts are by weight unless otherwise specified.

EXAMPLE 1 rosin was replaced with a completely hydrogenated wood rosin containing less than 1.0% dehydroabietic acid and 91% tetrahydro rosin acids (including tetrahydroabietic and tetrahydropimaric acids), was completely free of crystals after six weeks at 60 C. The determined properties of the two soaps are set forth in Table 1 below.

Table 1 Sodium soap of Sodium soap of disproportionated disproportionated rosin, 10% comrosin pletely hydrogenated rosin Total solids 75.5% 75.4%. Acid number 25.3 26.9. Crystalline content after Grossly crystalline N 0 crystals (microsix wccks at 60 0. scopic examination). Polymerization rate (as 6.7 6.3.

hours to 60% conver sion).

EXAMPLE 2 Table 2 Potassium soap of 85% disproportionated rosin, 15% substantially completely hydrogenated rosin Potassium soap of disproportionated rosin Total solids Acid number 18.

Crystalline content at Grossly crystalline 60 C. (3 weeks).

No crystals in 6 weeks (microscopic examinat1on).

EXAMPLE 3 A potassium soap of mixed fatty and rosin acids, in the approximate ratio of 1.221, was prepared in the following manner. One hundred ten parts of disproportionated rosin, similar to that utilized in Example 1, and 113 parts of hydrogenated tallow fatty acids were reacted with 73 parts of 45.5% potassium hydroxide and additional water. The product, after being seeded with crystals, was grossly crystalline after six weeks at 60 C.

he term grossly crystalline, as used herein, denotes that the soap, normally fluid at F., was crystallized to such an extent that all flow properties were lost at 140 F.

A similar soap in which 10% of the disproportionated rosin requirement was replaced with a substantially completely hydrogenated rosin, similar to that used in Example 1, contained only a microscopic trace of crystals after similar seeding, storage at 60 C., and observation for six weeks. The determined properties of the two soaps of mixed organic acids are set forth in Table 3 below.

Table 3 Potassium soap of Potassium soap of disproportionated disproportionated rosin, substantially rosin-fatty acid completely hydroinixture genated rosin, and

fatty acid Total solids 81.3% Acid number 23.4 23.2. Crystalline content after Grossly crystalline Trace of crystals.

six weeks at 60 C.

EXAMPLE 4 A potassium soap of mixed fatty and rosin acids, in the approximate ratio of 1.2: l, was prepared in the following manner. Disproportionated rosin (110 parts) and 113 parts of hydrogenated tallow fatty acids were reacted with 73 parts of 45.5% potassium hydroxide and additional water. The resulting soap, after being seeded with crystals, was grossly crystalline after five weeks at 60 C.

A similar soap was prepared in which 5% of the disproportionated rosin requirement was replaced with a substantially completelyhydrogenated rosin, similar to that used in Example 1. A portion of this soap was seeded in a similar manner, and after six weeks at 60 C. contained a moderate amount of crystals when observed microscopically. However, its flow properties at 140 F. were not affected.

A third similar soap was prepared in which of the disproportionated rosin requirement was replaced with a substantially completely hydrogenated rosin. After similar seeding, storage at 60 C., and observation for six weeks, this soap contained only a microscopic trace of crystals.

The properties of these analytically, were as follows:

three soaps, as determined Table 4 Potassium soap Potassium soap Potassium soap of (95%) disof (90%) disoi disproporproportionated proportionated tionated-rosinrosin, (5%) rosin, (10%) fatty acid tetrahydro tetrahydro mixture rosin acids, rosin acids,

and fatty acid and fatty acid Total solids 82.2%-- 81.4%-.- 81.7%. Acid number 23.5 23.0 24.1. Crystalline Grossly crystal- Mod. crystal Trace of crystals.

content, six line. growth. weeks at 60 C.

The rosin soaps of the invention are thus the alkali metal and particularly the sodium and potassium soaps' fatty acid mixtures containing from about 5% to about 20% by weight, based on the weight of disproportionated 1 rosin, of tetrahydro rosin acids or sufiicient substantially completely hydrogenated rosin to supply the indicated amount of tetrahydro rosin acids. The term substantially completely hydrogenated rosin, as 'used herein, denotes a hydrogenated rosin which has absorbed at least 1.22% hydrogen on the basis of the unhydrogenated rosin. These products may be prepared from any suitable type of rosin material such as gum rosin, wood rosin, tall oil rosin or the like and by any suitable methods such as those disclosed, for example, in US. 2,346,793and U.S. 2,776,276. A typical analysis of a substantially completely hydrogenated rosin of the type contemplated for use herein is as follows:

Tetrahydroabietic acid percent 68 'Tetrahydropimaric acid do 23 Dehydroabietic acid do 0.5 Acid number 160 The disproportionated rosin contemplated for use herein in preparing the soaps of the invention will generally contain less than 0.5% abietic acid and from about 40% to about 60% dehydroabietic acid, the remainder being mostly dihydro resin acids and a small amount of neutral materials. It may be prepared from any suitable rosin material including gum rosin, wood rosin and tall oil rosin and in any suitable manner as by a heat treatment in the presence of a catalyst such as iodine, sulfur dioxide,

platinum and the like. A suitable method for effecting disproportionation of rosin and rosin-fatty acid mixtures is disclosed in US. 2,138,183 to Edwin R. Littmann.

The soaps of the invention may also be prepared from disproportionated rosin-fatty acid mixtures. Mixtures 'of resistances to crystallization.

fatty acid mixture derived from tall oil. Suitable mixtures may also be obtained by mixing disproportionated rosin with other fatty acid mixtures such as acids contained in tallow or partially hydrogenated tallow.

The proportion of fatty acids in the mixture may vary widely but will usually be from about 50% to about 60% of the mixture. The fatty acids may, if desired, be hydrogenated or otherwsietreated to render them more suitable forthe purpose.

In ,the preparation of the soaps of the invention the tetrahydro rosin acids, as such, or as found is substantially completely hydrogenated rosin, may be added to the disproportionated rosin and the mixture then heated with aqueous alkali to form the soaps in the usual man- A ner. Alternatively, the tetrahydro rosin acids or substan: tially completely hydrogenated rosin, neutralized at least partially with alkali, may be added to the previously formed soap ,of disproportionated rosin or disproportionatedrosin-fatty acid mixtures. I j

The degree of saponification of thesoaps of the invention'may vary widely. In general, however, the. degree of saponification will vary from about 30%;to about 95% and preferably from about to about The amount of tetrahydro rosin acids or substantially completely hydrogenated rosin required for effective inhibition against crystallization willvary depending upon the acid number of the rosin and the acid number and solids content of the soap. In most cases it will be found that from about 6.5% to about 10% of tetrahydro rosin acids or an equivalent amount of substantially completely hydrogenated rosin, by weight based on the weight of disproportionated rosin, will be ample for the purpose. However, amounts up to about 20% maybe used in some cases. In general, amountsless than 5% will not provide the desired inhibition. against crystallization.

It will thus be seen that the presentinvention provides alkali metal soaps of disproportionated rosin and disproportionated rosin-fatty acid mixtures having improved Moreover, such soaps, when used in aqueous emulsion polymerization processes, give as good a. rate of polyrn-' :erization, and, in some cases, a better rate of polymerization, than soaps to which the crystallization inhibitor has not been added.

What I claim and desire to protect by Letters Patent is:

1. A rosin soap adapted for use as an emulsifier in aqueous emulsion polymerization processes, said soap being selected from the group consisting of sodiurn and potassium soaps of disproportionated rosin and mixtures of disproportionated rosin with fatty acids selected from the group consisting of tall oil fatty acids, hydrogenated tall oil fatty acids, tallow fatty acids, and hydrogenated tallow fatty acids, said-soap being stabilized against crystallization by having incorporated therein from about 5% to about 20% by weight, based on the weight of disproportionated rosin, of tetrahydro rosin acids, said tetrahydro rosin acids being neutralized to the extent of from about 30% to about 95 with a material selected from the group consisting of sodium and potassium hydroxides and carbonates. Y a

2. A soap adapted for use as an emulsifier in aqueous emulsion polymerization processes, said soap being selected from the group consisting of sodium and potassium soaps of mixtures of disproportionated rosin with fatty acids selected from the group consisting of tall oil fatty acids, hydrogenated tall oil fatty acids, tallow fatty acids,

and hydrogenated tallow fatty acids, said soap being stabiby having incorporated there by weight,'based on the of tetrahydro rosin acids, said tetrahydro lized against crystallization weight of rosin,

r'osinacids being-neutralized to the extent of fromabout 30% to about 95% with a material selected from the group consisting of sodium and potassium hydroxides and carbonates.

3. A rosin soap adapted for use as an emulsifier in aqueous emulsion polymerization processes, said soap being selected from the group consisting of sodium and potassium soaps of disproportionated rosin, said soap being stabilized against crystallization by having incorporated theren from about to about 20% by weight, based on the Weight of disproportionated rosin, of tetra hydro rosin acids, said tetrahydro rosin acids being neutralized to the extent of from about 30% to about 95 with a material selected from the group consisting of sodium and potassium hydroxides and carbonates.

4. A rosin soap adapted for use as an emulsifier in aqueous emulsion polymerization processes, said soap being selected from the group consisting of sodium and potassium soaps of disproportionated rosin, said soap being stabilized against crystallization by having incorporated theren a sufficient amount of partially neutralized substantially completely hydrogenated rosin to provide from about 5% to about 20% by Weight, based on the weight of disproportionated rosin, of tetrahydro rosin acids, said tetrahydro rosin acids being neutralized to the extent of from about 30% to about 95 with a material selected from the group consisting of sodium and potas sium hydroxides and carbonates.

5. A rosin soap adapted for use as an emulsifier in aqueous emulsion polymerization processes, said soap being selected from the group consisting of sodium and potassium soaps of mixtures of disproportionated rosin With fatty acids selected from the group consisting of tall oil fatty acids, hydrogenated tall oil fatty acids, tallow fatty acids, and hydrogenated tallow fatty acids, said soap being stabilized against crystallization by having incorporated therein a suflicient amount of partially neutralized substantially completely hydrogenated rosin to provide from about 5% to about 20% by weight, based on the weight of disproportionated rosin, of tetrahydro rosin acids, said tetrahydro rosin acids being neutralized to the extent of from about to about with a material selected from the group consisting of sodium and potassium hydroxides and carbonates.

References Cited in the file of this patent UNITED STATES PATENTS 2,138,183 Littmann Nov. 29, 1938 2,249,766 Humphrey July 22, 1941 2,285,333 Humphrey June 2, 1942 2,346,793 Schultz et al Apr. 18, 1944' 2,682,528 Vandenberg June 29, 1954 2,776,276 Glasebrook et al Jan. 1, 1957 

1. A ROSIN SOAP ADAPTED FOR USE AS AN EMULSIFIER IN AQUEOUS EMULSION POLYMERIZATION PROCESSES, SAID SOAP BEING SELECTED FROM THE GROUP CONSISTING OF SODIUM AND POTASSIUM SOAPS OF DISPROPORTIONATED ROSIN AAND MIXTURES OF DISPROPORTIONATED ROSIN WITH FATTY ACIDS SELECTED FROM THE GROUP CONSISTING OF TALL OIL FATTY ACIDS, HYDROGENATED TALL OIL FATTY ACIDS, TALLOW FATTY ACIDS, AND HYDROGENATED TALLOW FATTY ACIDS, SAID SOAP BEING STABILIZED AGAINST CRYSTALLIZATION BY HAVING INCORPORATED THEREIN FROM ABOUT 5% TO ABOUT 20% BY WEIGHT, BASED ON THE WEIGHT OF DISPROPORTIONATED ROSIN, OF TETRAHYDRO ROSIN ACIDS, SAID TETRAHYDRO ROSIN ACIDS BEING NEUTRALIZED TO THE EXTENT OF FROM ABOUT 30% TO ABOUT 95% WITH A MATERIAL SELECTED FROM THE GROUP CONSISTING OF SODIUM AND POTASSIUM HYDROXIDES AND CARBONATES. 